Two American swimmers broke world records at the world championships on Friday.

First was Caeleb Dressel winning the men's 100m butterfly semis at the FINA World Championships in 49.50. Dressel topped Michael Phelps' 10-year-old record by 0.32.

Caeleb Dressel of the United States celebrates after breaking the world record in the men`s 100m butterfly in the event`s semifinals at the FINA World Championships at Nambu University Municipal Aquatics Center in Gwangju, 330 kilometers south of Seoul, on July 26, 2019. (Yonhap)

Minutes later, Regan Smith set a new world record in the women's 200m backstroke, winning the semifinals at 2:03.35. The previous record, set by Missy Franklin of the United States in 2012, was 2:04.06.

Smith, 17, had set the junior world record in this event during the preliminary earlier Friday, with 2:06.01.

Six world records have been set or equaled so far in Gwangju, 330 kilometers south of Seoul. (Yonhap)